When Catelyn Stark negotiates with Lord Frey to gain permission for her son Robb Stark and his army to pass the The Twins, one of Walder's demands is for his son Olyvar be made Robb's squire, and for him to be knighted. Robb accept these terms.
and numerous mistresses
|Walder Frey||Joyeuse Frey|
|Stevron Frey||"Lame Lothar" Frey||Roslin Frey||Edmure Tully||"Black Walder" Rivers||Ryger Rivers|
|Roose Bolton||"Fat Walda" Frey|
In the books
In the A Song of Ice and Fire novels, Olyvar is the eighteenth son of Lord Walder overall and the fourth born to Lord Walder's sixth wife, Bethany Rosby. His three older brothers are Perwyn, Benfrey, Willamen, and his younger sister is Roslin. He is two years older than Robb Stark although he is very immature compared to Robb. He takes part in the Battle of the Whispering Wood.
When Robb breaks his marriage pact with House Frey, Olyvar wants to remain with him but is forced by his siblings to leave Robb. Olyvar is kept in the dark about his father's plan to betray and kill Robb Stark at the Red Wedding. It was feared that he was too loyal to Robb, and would try to warn him or even to defend him when the ambush commenced, so he is sent away from the Twins "on duty".
- Olyvar Frey at A Wiki of Ice and Fire (MAJOR spoilers from the books)
|Lord:||Lord Walder Frey||Heir:||Ser Stevron Frey|
|Seat:||The Twins · Riverrun||Lands:||Riverlands|
|Title(s):||Lord of the Crossing · Lord of Riverrun · Lord Paramount of the Trident|
|Current members:||Arwaya Frey · Derwa Frey · Freya Frey · Janeya Frey · Lothar Frey · Marianne Frey · Merry Frey · Neyela Frey · Olyvar Frey · Roslin Frey · Sarra Frey · Serra Frey · Shirei Frey · Walda Frey · "Fat Walda" Frey · Waldra Frey · Waldron Frey · Ryger Rivers · Black Walder Rivers|
|Deceased members:||Joyeuse Erenford|
|Household:||Malcolm · Talbot|
|Overlord:||House Baratheon of King's Landing|